Snap-action sequential multi-circuit switch



March 28, 1967 l SNAP AVCTION SEQUENTIAL MULTI-CIRCUIT SWITCH Filed 0G12. 20, 1965 E. R. CARLSON United States Patent fitice 3,311,716 SNAP-ACTION SEQUENTIAL MULTI-CIRCUIT SWITCH Ernest R. Carlson, Fairfield, Conn., assigner to Harvey Hubbell, Incorporated, Bridgeport, Conn., a corporation of Connecticut Filed Oct. 20, 1965, Ser. No. 498,855 9 Claims. (Cl. 200-6) This invention relates to a multi-circuit switch and, more particularly, to such a switch which is especially well adapted for use as a hospital call switch.

Hospitals for many years have employed call switches mounted on the wall above the head or the patients bed for actuation by the patient by means of a pull cord. These switches are n-ormally connected to energize three lights-one over the patients bed, one on the wall over the patients door, and a ilashing light on the nurses signal board. Hospital wiring design imposes the requirement ythat these individual lighting circuits be isolated from one another. Accordingly, these switches must be of the multi-circuit type wherein each of the three circuits is individually connected to, or disconnected from, the power supply. Switches which have been utilized for this function in the past have been of the snap acting D.C. type, -having two spring loaded rocker type -contact blades. The switch has four terminals, one being connected to the power supply and each of the `other three being connected to one of the signal circuits. The switch is constructed in such a manner that, in the on position, all four terminals are interconnected but, in the off position, all -four terminals are separated. The difficulty with D C. switches in this application is'that they are costly, are noisy, and require a substantial force in order to actuate them.

A.C. switches would be desirable as hospital call switches since they are inexpensive, quiet, and easily operated. However, four terminal A.C. switches are not normally designed to function in the desired manner, i.e.

` will be more apparent from the following description, the

appended claims and the figures of the attached drawing wherein:

FIG. l is a front view of a switch in accordance with the present invention, shown in its open position;

FIG. 2 is a right side view of the switch of FIG. l;

FIG. 3. is an enlarged front view of the switch of FIGS. l and 2 with the mounting strap, cover, and toggle removed;

FIG. 4 is a cross section taken substantially along the line 4 4 of FIG. 3, the switch being shown in its closed position;

FIG. 5 is a cross section taken substantially along the line 5-5 of FIG. 3;

FIG. 6 is a cross section taken substantially along the line 6-6 of FIG. l;

FIG. 7 is a partial cross section taken along the line 7-7 of FIG. 1; and

FIGS. 8-10, together with FIG. 7, illustrate the sequential operation of the switch of this invention.

The objects of this invention are achieved by providing a single pole multi-circuit switch including first and second 3,311,716 Patented Mar. 28, 1967 moving arms which are movable, respectively, against first and second fixed contacts. The switch is improved by the provision of a resilient shunt member which has a first end secured to the rst contact of the switch and a second end intermediate the second fixed contact and its movable arm. The second end is normally biased away from the second fixed contact but is movable thereagainst by said arm.

With particular reference to the drawings, there is illustrated a switch comprising a substantially hollow rectangular housing 10, a cover 12, a toggle 14, and a mounting strap 16. The housing, cover, and toggle are made of insulating material and the mounting strap is metal in accordance with the usual construction of switches of this general type. A hole is provided in the toggle for securing the end of a pull cord 18, by means of which the patient may pull the toggle downward and close the switch. Each side of the housing 10 defines a generally semicircular opening 2t), 22, 24, 26 at either end thereof adjoining the top edge of the housing. The housing includes a pair of centrally positioned barriers, 28, 30 which extend inwardly from either end of the housing. Each barrier carries at its innermost end a rubber bumper disc 32, 34. A portion of barrier 30 is cut away at an angle, as shown in FIGS. 7-10, to provide a stop 36 whose function will be further explained below. A spring positioning stud 38 is formed in the bottom of housing 10 intermediate the barriers 28, 30. The side walls of the housing 10 include a pair of cutout portions 40 for supporting the axial pivot studs 42 of the toggle 14.

The toggle 14 is of the usual construction and includes a pair of inwardly extending operating cams 44, 46 positioned on opposite sides of the hollow housing. A molded pin 48 on the bottom of the toggle 14 receives the upper end ot the coil spring 50. The bottom end of the coil spring is retained by stud 38. The toggle is held in place by the cutout portions 4t) against the `force of the coil spring by means of a cover 12 which includes a rectangular opening 52 for the toggle and recesses 54 for receiving the toggle pivot studs 42. The cover also includes a rectangular terminal opening 56, aligned with each of the semicircular openings 20, 22, 24, 26 of housing 19. The mounting strap 16 is positioned atop the cover 12 and the entire assembly is held together by means of screws 58 which pass through the housing and cover and threadedly engage the mounting strap.

Both the housing and the cover are provided 'with slots on their inner surfaces adjacent the four semicircular openings and the four terminal openings. Mounted within these slots and across each of the openings, there is an electrical terminal plate. These include a supply terminal plate 60 and three load terminal plates 62, 64, 66. Each terminal plate is apertured to receive a terminal screw 68 which threadedly engages a wire clamping plate 70. The housing l0 defines wire-receiving openings '71, each of which permits the end of a conductor to be inserted between a clamping plate 70 and the respective terminal plate when the terminal screw 68 is loosened. Each of the terminal plates 60, 64 is the outer vertical arm of a substantially U-shaped structure which includes a horizontal member and a vertical inner member. Thus the supply terminal plate 60 is integral with horizontal member 72 and vertical member 74 |which is positioned against one side of barrier 28 as shown in FIG. 3. Similarly, load terminal plate 64 is integral with hoizontal member 76 and vertical member 78 which is mounted against the other side of barrier 28 as seen in FIG. 3.

The load terminal plate 62 is the upright portion of a generally L-shaped member which includes a `horizontal leg 80 terminating in a short vertical lip 82 mounted against a molded inner projection 84 on theinner end wall of housing 10. Riveted against the lower surface of 'J sa horizontal leg 80 is an electrical contact disc 86 (FIG. 7). The load terminal plate 66 is the vertical portion of an L-shaped contact member which includes a horizontal leg 88. Mounted against the lower surface of the horizontal leg 88 is one end of a transversely extending resilient shunt 90 (FIG. 8) secured thereto by means of a contact disc 92 which is riveted thr-ough the shunt into the horizontal leg 88. Shunt 90 angles downwardly across the width of the housing above the stop 36 and carries at its opposite end a double contact disc 94 protruding from both its upper and lower surfaces.

Mounted against the lower surface of horizontal member '72, by means of a rivet 96, is `one end of an elongated resilient moving arm 98. In elevational view, the `moving arm 98 is substantially U-shaped, as shown in FIG. 4, and includes a raised planar central portion 100 lying in the path of travel of loperating carn 46. The free end of arm 98 carries an electrical contact disc 102 which is vertically aligned with contact discs 94 and 86. The natural resiliency of moving arm 98 causes its free end to be biased upwardly against the free end of shunt 90, tending to cause the moving arm 98, the shunt 90, and the load terminal plate 62 to be in electrical contact with one another as illustrated in FIGS. 4 and 10.

A somewhat similar moving arm 104 is mounted in the opposite side of the housing and is generally parallel to arm 98. One end of this arm is secured to horizontal member 76 by means `of rivets 106 and it will be noted from FIG. 5 that its planar central portion 10S is in a higher plane than t-he similar portion of moving arm 98.

The free end of the moving arm 104 carries on its upper surface a Contact disc 110 which is aligned lwith contact disc 92.

OPERATION Since the switch of this invention is designed for operation by pull cord 18, it is mounted to be operated in a reverse fashion from most wall mounted switches. In other words, when the toggle 14 is up, as illustrated in FIGS. 1 and 2, the switch is open, but when pulled to the down position, as in FIGS. 3-5, the switch is closed. The switch is installed with the end of a power supply conductor clamped between supply terminal plate 60 and its i wire clamping plate 70. The conductor to each of the three loads to be controlled is then connected in a similar manner to one of load terminal plates 62, 64, 66. When the switch is in the open position, illustrated in "FIGS. 1, 2, 6 and 7, the operating cams 44, 46 bear downward against the central porti-ons 100, 108 tof the moving arms 98, 104. The free ends of these arms are thus biased downwardly, as shown in FIG. 7, so that the contact discs 102, 110 are spaced from contact discs 86, 92 associated, respectively, with load terminal plates 62, 66.

In addition, shunt 90, which is resilient and normally l wardly, lshifting the toggle to its downward position. The

toggle has the customary snap action-compressing the spring 50 until past its dead center position and, thereafter, being forced into its downward position by expansion of spring 50. ADuring this movement, the sequence of events shown in FIGS. 7-10 takes place. As the cams 44, 46 begin to release their corresponding moving arms, their free ends begin to move upwardly at approximately the same rate. Because of the relatively small clearance between contact disc 102 and the lower of double contact disc 94, moving arm 98 makes contact with the shunt 90, as shown in FIG. 8. This immediately makes an electrical connection between supply terminal 60 and load terminal 66, energizing one of the controlled circuits. As the toggle continues to pivot, the moving arms continue to move upwardly and arm 98 now forces the free end of shunt 90 upwardly with it. The upper contact disc 4on shunt now contacts the disc 86 associated with load terminal plate 62, as shown in FIG. 9, so that this load terminal is also connected to the power supply, energizing the second controlled circuit. Further motion of the toggle permits moving arm 104 to move to its upper limit, allowing the contact disc to come into contact with disc 92 associated with load terminal plate 66, as shown n in FIG. l0. This cnergizes the terminal plate 64, adding the third controlled circuit to the power supply. It will thus be seen that actuation of the switch has energized three different circuits, but in a sequential manner, thereby keeping arcing to a minimum.

The loads are disconnected in the reverse manner. Reference to FIGS. 4 and 5 will disclose that operating cam 44 is in contact with moving arm 104 but that operating cam 46 is Out of contact with moving arm 98. Upon actuation of toggle 14, therefore, moving arm 104 is depressed first so that it breaks contact as shown in FIG. 9. Further movement of the toggle causes cam 46 to depress moving arm 98 to release the holding force against shunt 90, causing it to break electrical contact with terminal plate 62. This breaks the second load circuit, as shown in FIG. 8. Finally stop 36 prevents further downward motion of shunt 90, releasing it from the downwardly moving arm, as shown in FIG. 7, thus disconnecting the third circuit connected to terminal plate 66. Thus, the three load circuits are broken in sequence.

As a variation in the use ot the disclosed switch, the terminal plate 64 may be connected to the power supply and terminal plate 60 to one of the loads.` The switch would still maintain the circuits isolated from one another when in its open position. However, all circuits would be simultaneously energized or deenergized at contact discs 92, 110.

It is believed that the many advantages of this invention will be apparent to those skilled in the art. It is also understood that a number of variations and modifications will be apparent which do not depart from the spirit and scope of this invention. Accordingly, the foregoing description is to be construed as illustrative only, rather than limiting. This invention is limited only Iby the scope of the following claims.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a switch including first and second arms movable, respectively, against first and second fixed contacts and means for selectively moving said arms against said fixed contacts, the improvement which comprises: a resilient conductive shunt member having a first end secured to the first fixed contact of said switch and a second end intermediate the second fixed contact and said second arm, said second end being normally displaced from said second xed contact but movable thereagainst by said second arm.

2. The switch of claim 1 wherein the second end of said shunt is spaced from said second arm when the switch is in its `open condition.

3. A switch for controlling multiple circuits which comprises: a housing; first and second arm members within said housing, each having a fixed first end and a second end movable between an open and a closed position; a first fixed contact spaced from the second end of said first arm member when said first arm member is in its open position; a second fixed contact spaced from the second end of said second arm member when said second arm mem-ber is in its open position; resilient conductive shunt means having a first end secured to said second fixed contact and a movable second end positioned between said rst fixed contact and the second end of said first arm member and displaced therefrom when said arm members are in their open positions, said movable second end of said shunt means being normally biased away from said first fixed contact but movable thereagainst by said first arm member when moved into its closed position; means for making an external wiring connection to is a toggle.

6. The switch of claim 3 wherein each of said arm members is resiliently biased toward its closed position and wherein said actuating means comprises a toggle including a rst operating cam positioned to fiex said first arm member to its open position and a second operating cam positioned to fiex said second arm member to its open position.

7. The switch of claim 6 wherein said second arm member opens before, and closes after, said first arm member.

8. A switch for controlling multiple circuits which comprises: a housing; first Iand second switch arm members within said housing, each having a fixed first end and a second end movable between an open and a closed position; first wiring terminal means connected to the first end of said first arm member; second wiring terminal means connected to the first endof said second arm member; a first fixed contact spaced from the second end of said first arm member when said first arm member is in its open position; third wiring terminal means connected to said first fixed contact; a second fixed contact spaced from the second and of said second arm member when said second arm member is in its open position; fourth wiring terminal means connected to said second fixed contact; elongated resilient conductive shunt means having a rst end secured to said second fixed contact and a movable second end positioned between said first fixed contact and the second end of said first'arm member and displaced therefrom when said arm is in its open position, said movable second end being normally biased away from said first fixed contact; stop means positioned to engage said shunt means to prevent engagement lof its movable end with the second end of said first arm membei when said -arm member is in its open position; and actuating means for sequentially engaging the first arm member with said shunt means, said shunt means with said first fixed contact, and said second arm member with said second fixed contact, and for disengaging in the reverse sequence.

9. The switch of claim 8 wherein each of said arm members is resiliently biased toward its closed position and wherein said ac-tuating means comprises a toggle including a first operating cam positioned to flex said first arm member to its open position and a second operating cam positioned to ex said second arm member to its open position.

References Cited by the Examiner UNITED STATES PATENTS 2,854,534 9/1958 Beauclair 200-27 X ROBERT K. SCHAEFER, Primary Examiner. I. R. SCOTT, Assistant Examiner. 

1. IN A SWITCH INCLUDING FIRST AND SECOND ARMS MOVABLE, RESPECTIVELY, AGAINST FIRST AND SECOND FIXED CONTACTS AND MEANS FOR SELECTIVELY MOVING SAID ARMS AGAINST SAID FIXED CONTACTS, THE IMPROVEMENT WHICH COMPRISES: A RESILIENT CONDUCTIVE SHUNT MEMBER HAVING A FIRST END SECURED TO THE FIRST FIXED CONTACT OF SAID SWITCH AND A SECOND END INTERMEDIATE THE SECOND FIXED CONTACT AND SAID SECOND ARM, SAID SECOND AND END BEING NORMALLY DISPLACED FROM SAID SECOND FIXED CONTACT BUT MOVABLE THEREAGAINST BY SAID SECOND ARM. 